Objectives, Rationale and Specific Aims The primary purpose of the Exposure Assessment Facility Core is to enhance the research capabilities of Center for Environmental Health in Northern Manhattan (CEHNM) investigators by providing expertise in a number of related activities and services not available elsewhere in the University, including exposure design, method development, sampling and analysis. This Facility Core supports the development and implementation of exposure assessments in support of funded research, pilot studies, new research initiatives, and outreach activities of the CEHNM by coordinating the following services and activities: study design, methods development, design and development of new sampling equipment, air sampling, and analytical capabilities; expansion of these facilities and efforts in ways that support the evolving strategic goals of the CEHNM; . training and mentoring of staff, students and researchers; responding to exposure emergencies; responding to the needs of the Community Outreach and Education Core (COEC) and local community ograniziations in a number of ways, including testifying in public hearings and carrying out pilot field work to test whether perceived sources of air pollution exist and can be documented. This Facility Core combines analytical capabilities and expertise at the Mailman School of Public Health (MSPH) and Lamont-Doherty Earth Observatory (LDEO). The primary focus of the Exposure Assessment Facility Core is on sampling and analysis of environmental rather than biological samples. The analysis of biomarkers of exposure are addressed by the Trace Metals Facility Core and the Integrative Health Sciences Facility Core, with the exception of lead isotope ratios in blood, which are analyzed at LDEO. A major strength of the CEHNM is the multiple working groups that are developing new initiatives and projects. Members of the Exposure Core participate in many of these groups to assist in the design of new exposure methods and markers that address specific research goals